[PLUGIN] Add plugin system

src/data/data.cc

@@ -255,5 +255,8 @@ std::string SparsePage::Format::DecideFormat(const std::string& cache_prefix) {
     return "raw";
   }
 }
+
+// List of files that will be force linked in static links.
+DMLC_REGISTRY_LINK_TAG(sparse_page_raw_format);
 }  // namespace data
 }  // namespace xgboost

src/data/sparse_batch_page.h

@@ -155,7 +155,7 @@ class SparsePage::Format {
    * \brief save the data to fo, when a page was written.
    * \param fo output stream
    */
-  virtual void Write(const SparsePage& page, dmlc::Stream* fo) const = 0;
+  virtual void Write(const SparsePage& page, dmlc::Stream* fo) = 0;
   /*!
    * \brief Create sparse page of format.
    * \return The created format functors.

src/data/sparse_page_dmatrix.h

@@ -71,7 +71,7 @@ class SparsePageDMatrix : public DMatrix {
   /*! \brief page size 256 MB */
   static const size_t kPageSize = 256UL << 20UL;
   /*! \brief Maximum number of rows per batch. */
-  static const size_t kMaxRowPerBatch = 32UL << 10UL;
+  static const size_t kMaxRowPerBatch = 64UL << 10UL;
 
  private:
   // declare the column batch iter.

src/data/sparse_page_raw_format.cc

@@ -4,11 +4,14 @@
  *  Raw binary format of sparse page.
  */
 #include <xgboost/data.h>
+#include <dmlc/registry.h>
 #include "./sparse_batch_page.h"
 
 namespace xgboost {
 namespace data {
 
+DMLC_REGISTRY_FILE_TAG(sparse_page_raw_format);
+
 class SparsePageRawFormat : public SparsePage::Format {
  public:
   bool Read(SparsePage* page, dmlc::SeekStream* fi) override {
@@ -73,7 +76,7 @@ class SparsePageRawFormat : public SparsePage::Format {
     return true;
   }
 
-  void Write(const SparsePage& page, dmlc::Stream* fo) const override {
+  void Write(const SparsePage& page, dmlc::Stream* fo) override {
     CHECK(page.offset.size() != 0 && page.offset[0] == 0);
     CHECK_EQ(page.offset.back(), page.data.size());
     fo->Write(page.offset);